1. Field of the Invention
The present invention is directed to a method for producing a sequence of volume datasets on the basis of two volume datasets.
2. Description of the Prior Art
It is known from the literature, such as, for example, Detlef Ruprecht, “Geometrische Deformationen als Werkzeug in der graphischen Datenverarbeitung”, Dissertation of the University of Dortmund, 1994, pages 146–149 (also published in the Shaker Verlag, Aachen, 1995), to produce that an image sequence from two-dimensional images of an exposure subject by means of deformed dissolving, for example “morphing”. The image sequence begins with one of the images, the initial image, and ends with the other image, the target image. Intermediate images needed for the image sequence are generated from the initial image and the target image by means of interpolation techniques. First, point pairs of the initial image and the target image that correspond to one another are identified. A deformation of the initial image onto the target image and a deformation of the target image onto the initial image are calculated with the corresponding point pairs. The intermediate images are calculated by means of attenuated deformation. The picture elements of the initial or target image are displaced by only a part of the path determined by the deformation. Obtained as a result are a series of increasingly deformed images that proceed from the initial image and a series of decreasingly deformed images that leads to the target image. Subsequently, the two series are dissolved, resulting in a series of two-dimensional images that begins with the initial image and ends with the target image.
In the context of a medical follow-up study, for example, modality exposures of a patient are made at different points in time in order, for example, to recognize the changes in position and shape of tissue structures of the patient. One example of a follow-up study is the observation of a tumor treatment of the patient. For example, a physician treating the patient registers tomograms of the patient with a computed tomography system before and during the tumor treatment and compares them. An evaluation of the tomograms is difficult because the tomograms do not create any spatial impression.
It is also common to produce a CT exposure of the heart into which a heart catheter is introduced, before the introduction of a heart catheter. During the introduction of the heart catheter, the CT exposure is dissolved with ECG-triggered X-ray exposures of the heart in order to monitor the position of the heart catheter or to designationally control the heart catheter relative to the anatomy of the heart. The position of the catheter relative to the anatomy of the heart can vary greatly due to the contraction and relaxation of the heart muscle, so that it would be desirable to also display the dissolving at points in time other than the discrete point in time of the CT exposure, to enable visualization of the position of the catheter relative to the pre-operatively registered CT exposure at any time. In order to realize this, a sequence of CT exposures that essentially covers the entire time span of the heart rhythm would have to be registered before the intervention. This cannot be done in practice because it would expose the patient to an excessively high radiation load.